1. Field of the invention:
The present invention relates to a lens array and a lens array assembly used for e.g. an image reading apparatus.
2. Description of the Related Art:
As is known, a typical image reading apparatus includes a plurality of light receiving elements arranged in a line for receiving light reflected on a document to be read. For enabling proper image reading operation, the reflected light needs to be accurately focused onto the light receiving elements. To this end, use may be made of a lens array provided with an array of focusing lenses.
In a conventional lens array, a plurality of convex lenses (made of e.g. glass) are linearly arranged at regular intervals and held together by a resin holder prepared separately from the lenses. In place of the convex lenses, self-focusing lenses may be used for obtaining a non-inverted and non-magnified image.
The conventional lens array has the following disadvantage. As mentioned above, the plurality of the lenses and the holder are prepared separately, to be combined later. In this manner, however, the assembling process of the lens array tends to become complicated due to many small lenses (their diameter may be less than 1 mm) to be handled. Consequently, the yield of the conventional lens arrays is rather low, and the production cost becomes unduly high.
The present invention has been proposed under the circumstances described above. It is, therefore, an object of the present invention to provide an inexpensive lens array having an excellent optical performance.
Another object of the present invention is to provide a lens array assembly incorporating such a lens array.
According to a first aspect of the present invention, there is provided a lens array including a plurality of lenses and a holder formed integral with the lenses. Each of the lenses includes a first lens surface and a second lens surface. The second lens surface is flat. The holder includes a first surface adjacent to the first lens surface and a second surface adjacent to the second lens surface. A plurality of recesses are formed in the second surface of the holder.
Preferably, the lenses and the holder may be made of a transparent synthetic resin material.
Preferably, the recesses and the lenses are arranged alternately.
Preferably, the first lens surface of each lens may be convex or concave.
Preferably, each of the recesses of the holder may be provided with dark-colored light shielding means.
Preferably, the second surface of the holder may be covered with dark-colored light shielding means defining the second lens surface of each lens.
Preferably, the second lens surface of each lens may project from the second surface of the holder.
Preferably, the first surface of the holder may be covered with dark-colored light shielding means.
According to a second aspect of the present invention, there is provided a lens array assembly including at least first and second lens arrays. The first lens array includes a plurality of first lenses and a first holder formed integral with the first lenses, while the second lens array includes a plurality of second lenses and a second holder formed integral with the second lenses. The second lens array is fixed to the first lens array. Each of the first lenses includes a non-flat first lens surface and a flat second lens surface opposite to the first lens surface. The first holder is formed with a plurality of recesses adjacent to the second lens surfaces.
Preferably, the first lens array may be formed with a positioning hole, and the second lens array may be formed with a projection fitted into the positioning hole.
Preferably, each of the second lenses may include first and second lens surfaces which are both convex.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.